rippled/modules/ripple_app/ledger/LedgerTiming.cpp

//------------------------------------------------------------------------------
/*
    Copyright (c) 2011-2013, OpenCoin, Inc.
*/
//==============================================================================

// VFALCO Should rename ContinuousLedgerTiming to LedgerTiming

struct LedgerTiming; // for Log

SETUP_LOG (LedgerTiming)

// NOTE: First and last times must be repeated
int ContinuousLedgerTiming::LedgerTimeResolution[] = { 10, 10, 20, 30, 60, 90, 120, 120 };

// Called when a ledger is open and no close is in progress -- when a transaction is received and no close
// is in process, or when a close completes. Returns the number of seconds the ledger should be be open.
bool ContinuousLedgerTiming::shouldClose (
    bool anyTransactions,
    int previousProposers,      // proposers in the last closing
    int proposersClosed,        // proposers who have currently closed this ledgers
    int proposersValidated,     // proposers who have validated the last closed ledger
    int previousMSeconds,       // milliseconds the previous ledger took to reach consensus
    int currentMSeconds,        // milliseconds since the previous ledger closed
    int openMSeconds,           // milliseconds since the previous LCL was computed
    int idleInterval)           // network's desired idle interval
{
    if ((previousMSeconds < -1000) || (previousMSeconds > 600000) ||
            (currentMSeconds < -1000) || (currentMSeconds > 600000))
    {
        WriteLog (lsWARNING, LedgerTiming) <<
                                              boost::str (boost::format ("CLC::shouldClose range Trans=%s, Prop: %d/%d, Secs: %d (last:%d)")
                                                      % (anyTransactions ? "yes" : "no") % previousProposers % proposersClosed
                                                      % currentMSeconds % previousMSeconds);
        return true;
    }

    if (!anyTransactions)
    {
        // no transactions so far this interval
        if (proposersClosed > (previousProposers / 4)) // did we miss a transaction?
        {
            WriteLog (lsTRACE, LedgerTiming) << "no transactions, many proposers: now (" << proposersClosed << " closed, "
                                                << previousProposers << " before)";
            return true;
        }

#if 0 // This false triggers on the genesis ledger

        if (previousMSeconds > (1000 * (LEDGER_IDLE_INTERVAL + 2))) // the last ledger was very slow to close
        {
            WriteLog (lsTRACE, LedgerTiming) << "was slow to converge (p=" << (previousMSeconds) << ")";

            if (previousMSeconds < 2000)
                return previousMSeconds;

            return previousMSeconds - 1000;
        }

#endif
        return currentMSeconds >= (idleInterval * 1000); // normal idle
    }

    if ((openMSeconds < LEDGER_MIN_CLOSE) && ((proposersClosed + proposersValidated) < (previousProposers / 2 )))
    {
        WriteLog (lsDEBUG, LedgerTiming) << "Must wait minimum time before closing";
        return false;
    }

    if ((currentMSeconds < previousMSeconds) && ((proposersClosed + proposersValidated) < previousProposers))
    {
        WriteLog (lsDEBUG, LedgerTiming) << "We are waiting for more closes/validations";
        return false;
    }

    return true; // this ledger should close now
}

// Returns whether we have a consensus or not. If so, we expect all honest nodes
// to already have everything they need to accept a consensus. Our vote is 'locked in'.
bool ContinuousLedgerTiming::haveConsensus (
    int previousProposers,      // proposers in the last closing (not including us)
    int currentProposers,       // proposers in this closing so far (not including us)
    int currentAgree,           // proposers who agree with us
    int currentFinished,        // proposers who have validated a ledger after this one
    int previousAgreeTime,      // how long it took to agree on the last ledger
    int currentAgreeTime,       // how long we've been trying to agree
    bool forReal,               // deciding whether to stop consensus process
    bool& failed)               // we can't reach a consensus
{
    WriteLog (lsTRACE, LedgerTiming) << boost::str (boost::format ("CLC::haveConsensus: prop=%d/%d agree=%d validated=%d time=%d/%d%s") %
                                        currentProposers % previousProposers % currentAgree % currentFinished % currentAgreeTime % previousAgreeTime %
                                        (forReal ? "" : "X"));

    if (currentAgreeTime <= LEDGER_MIN_CONSENSUS)
        return false;

    if (currentProposers < (previousProposers * 3 / 4))
    {
        // Less than 3/4 of the last ledger's proposers are present, we may need more time
        if (currentAgreeTime < (previousAgreeTime + LEDGER_MIN_CONSENSUS))
        {
            CondLog (forReal, lsTRACE, LedgerTiming) << "too fast, not enough proposers";
            return false;
        }
    }

    // If 80% of current proposers (plus us) agree on a set, we have consensus
    if (((currentAgree * 100 + 100) / (currentProposers + 1)) > 80)
    {
        CondLog (forReal, lsINFO, LedgerTiming) << "normal consensus";
        failed = false;
        return true;
    }

    // If 80% of the nodes on your UNL have moved on, you should declare consensus
    if (((currentFinished * 100) / (currentProposers + 1)) > 80)
    {
        CondLog (forReal, lsWARNING, LedgerTiming) << "We see no consensus, but 80% of nodes have moved on";
        failed = true;
        return true;
    }

    // no consensus yet
    CondLog (forReal, lsTRACE, LedgerTiming) << "no consensus";
    return false;
}

int ContinuousLedgerTiming::getNextLedgerTimeResolution (int previousResolution, bool previousAgree, int ledgerSeq)
{
    assert (ledgerSeq);

    if ((!previousAgree) && ((ledgerSeq % LEDGER_RES_DECREASE) == 0))
    {
        // reduce resolution
        int i = 1;

        while (LedgerTimeResolution[i] != previousResolution)
            ++i;

        return LedgerTimeResolution[i + 1];
    }

    if ((previousAgree) && ((ledgerSeq % LEDGER_RES_INCREASE) == 0))
    {
        // increase resolution
        int i = 1;

        while (LedgerTimeResolution[i] != previousResolution)
            ++i;

        return LedgerTimeResolution[i - 1];
    }

    return previousResolution;
}